You are correct. These and those are very specific and also include a statement on position. These = the specific ones here. Those= the specific ones there.
'They' is perfectly acceptable for inanimate objects, animals etc. It is the plural of 'it' with no 'position/place' or necessarily a specific element to what you are saying.
For example. Meercats are animals. They live in large family groups.
We can't say 'these' live in family groups as we are talking about all the meercats in the world, not just a group that is near us. Likewise, 'those' would be pointing out a specific group some distance from us. Both options suggest that this is not necessarily normal behaviour for meercats, and that other meercats may not be living in family groups, which is incorrect.
I don't know where your friend got that idea from but it must make their English-speaking very difficult! How does he/she cope with situations such as 'I want to return these shoes as they don't fit me' or 'I want to order some dining chairs please and they must match my oak table'. You can't substitute 'those' or 'these' for either of those 'they's.